The present invention is directed primarily to the bleaching of greige cloth, and secondarily to the operations normally attendant to the bleaching operation itself. In a conventional, commercial bleaching operation, the greige cloth is first batched into a continuous web of appropriate length, and then is conveyed in "rope" form through a series of operations. Typically, the fabric is directed into a wetting-out solution, which makes the fibers more readily receptive to the bleach solution. The wet-out fabric is then conveyed in a continuous succession through a bleaching kier, "J" box or other vessel, in which it is exposed to the bleaching solution. From the bleaching vessel, the fabric is conveyed to a washing vessel, where it is washed (and/or other finishes are applied), and then to an opening and stretching stage, in which the fabric rope is returned to its initial, flat web form and restored to desired width. The open fabric is then conveyed through a dryer stage and converted to rolled or folded batches of desired length for further handling.
In accordance with the present invention, an improved system and procedure is provided which enables the bleaching and attendant operations to be carried out at greatly increased rates of speed and with less equipment and fewer personnel. In the process of the invention, for example, the fabric bleaching operation may be reduced in time from a conventional period of three to five hours to a period of around five to ten minutes. At the same time, many of the handling problems and production problems experienced in the conventional processing techniques, are avoided.
In accordance with the present invention, the greige fabric, which may be either knitted or woven, is rolled upon a hollow, perforate core tube. In some cases, the fabric may be wound up in the first instance on such a tube as it comes off of the knitting machine or loom. A plurality of the thus wound rolls of fabric are placed in a rack and loaded into a pressure vessel. The rack and vessel, which in themselves may be of known construction, provide for the rolls of fabric to be supported for rotation internally of the vessel, and the perforated core tube for each of the rolls is connected individually to a fluid inlet line.
In accordance with one aspect of the invention, the individual inlet lines to the respective cloth rolls are connected through individual heat exchange units, and individual pumps and valves, to a retention tank for bleach solution. The bleach solution is pumped into the pressure vessel through the individual pumps and heat exchangers, such that the bleach solution is heated after passing through the pumps, and enters the pressure vessel at a substantially elevated temperature. The bleach solution flows into the individual core tubes and then radially outward through the individual rolls of cloth into the interior of the pressure vessel. Desirably, the individual rolls are mechanically rotated while the bleach solution is being flowed therethrough, to provide more effective agitation and distribution of the solution. The pressure vessel has a valved outlet, leading back to the solution retention tank. The valved outlet enables the liquid within the vessel to be controllably maintained under a superatmospheric pressure appropriate to the solution and its temperature, to prevent vaporization of the solution within the vessel.
By effecting a force flow of the bleach solution through the cloth roll, at substantially elevated temperatures relative to conventional processing, and by carrying out the bleaching of the fabric in roll form, it is possible to complete the bleaching of the entire roll within a few minutes, as compared to several hours under conventional procedures.
As a further feature of the invention, the various operations normally attendant to the primary bleaching operation are also carried out while the cloth rolls are housed within the pressure vessel. Thus, prior to introducing the bleach solution, appropriate cleaning and wetting solutions, in conjunction with optical dyes if desired, may be introduced into the cloth by means of the pumps and lines subsequently used for circulating the bleach solution. Likewise, washing operations and the addition of finishing solutions may be introduced through the bleach system, after the bleaching operation has been completed and while the fabric rolls remain within in the processing vessel. Moreover, through the use of radio frequency magnetic energy, by techniques known in the trade and, in themselves, forming no part of the present invention, the wet-processed rolls may be dried while they remain within the processing vessel and in roll form. Thus, pursuant to the invention, dry greige fabric rolls are introduced into the processing vessel, and rolls of dry bleached and finished fabric are removed therefrom after a relative few minutes of processing.
For a better understanding of the above and other features of the invention, reference should be made to the following description of a preferred embodiment thereof and to the accompanying drawings.